My opinion? You play to win the next game.
I think this is that you treat it as wrong way to think about it. And quite frankly, you being a former college football player, I am a bit surprised that you advocate it. What kind of message does it send to the rest of the team when a coach does not maximize the chances to win this week. Absent injury concerns, a coach should ALWAYS do that. ALWAYS.
I think your flaw is that you treat it as almost a certainty that we'd be worse off with one of the younger guys. There's nothing at all to show that's the case. Like I said we're trending toward 100 in offensive ranking and we've only faced one defense in the top 50. I find it hard to believe any of them are worse than that. For context, LDR's QBR of 42 is/was worse than every QB that have played here in the past 5 years. The only QB who had a worse QBR in their time starting was Driskel in 13' when he played 3 games. So if having the best chance to win is the goal, why are they still playing? Literally the only thing anyone points to in support of them is that their competitors are inexperienced. Well isn't it an indictment on them that they're performing so poorly despite their experience?
And my view lines up with what I've always seen. From HS to college the coaches always tell you...if the younger guy is even comparable to you they're playing him. Why? Because they get him for 3-4 more years. That's how it is so you have to leave no doubt about who is the better player if you're the upperclassmen. Do you feel LDR or Appleby have left no doubt that what's on the bench isn't better? I don't.